Earth-working machines, for example, excavators, continuous miners, loaders, often include tracked undercarriages that facilitate movement of the machines over ground surfaces. Such track-type machines typically include tracks located on either side of the machine. Each track includes a chain having links pinned end-to-end forming a loop that extends around a drive sprocket at one end of the chain and an idler wheel located at the other end of the chain. Some machines may include additional idler wheels to guide the chain from the sprocket end to the idler wheel end. The chains often also include ground engaging track shoes connected to adjacent pairs of links. An engine associated with the machine typically drives the sprocket. Teeth on the sprocket engage with the links to rotate the chain, pushing the track shoes against a work surface and allowing the machine to be propelled in a forward or rearward direction.
Repeated contact between the sprocket teeth and the links causes the teeth and the links to wear over time, creating slack in the chains between the sprocket and the one or more idler wheels. Slack in the chains can cause the chains to wear excessively, break, or to slip off the drive sprocket and idler wheels. Repairing broken or displaced chains may require expensive and labor intensive service operations, which can place the machine out of service for a long time. Thus, minimizing wear of the sprocket teeth and track shoes becomes important to reduce excessive slack formation and to prevent premature failure of the chains.
U.S. Pat. No. 8,070,240 of Zheng et al. that issued on Dec. 6, 2011 discloses a sprocketed drive assembly for a track-type machine. In particular, the '240 patent discloses a sprocket assembly having a plurality of teeth, where each successive pair of teeth defines a substantially concave channel for receiving a cylindrical pin member associated with a link member of a continuous track chain. The '240 patent further discloses that each tooth has a tooth angle of about 17 degrees measured between a flat portion of a tooth flank and a radial axis passing midway between adjacent teeth. The '240 patent discloses that decreasing the tooth angle of the drive sprocket makes the sprocket teeth steeper, which increases the rotational force needed for the chain to slip or jump over the steeper tooth angle, potentially limiting the occurrence of sudden track movement also known as “track jump.”
Although the '240 patent discloses a sprocket designed to reduce track jump, the disclosed sprocket may still be less than optimal. In particular, the use of a concave channel between adjacent teeth may cause the link member engaged by a tooth to have a line contact with the tooth flank. Line contact between the link member and the tooth may have the effect of concentrating the contact force over a relatively small surface area of the tooth, which may increase the amount of wear experienced by the tooth and the link member, contributing to generation of slack in the track chain.
The sprocket of the present disclosure solves one or more of the problems set forth above and/or other problems of the prior art.